Anti-government protesters clash with riot police in Kiev's Independence Square. Photo: AP
"We must be clear: ultimate responsibility for deaths and violence is with president Yanukovych. He has blood on his hands," Bildt said on Twitter.
"Hoping for strong unity in parliament today against violence and repression in Ukraine. People are being shot to death on the streets of a European capital."
Kiev has been wracked by anti-government demonstrations since President Viktor Yanukovych in November rejected an EU pact in favour of closer ties with Russia.
Demonstrations against Yanukovych's rule descended into violence on Tuesday for the first time in weeks, causing at least 25 deaths.
Bildt said on Tuesday that he supported sanctions against the Ukrainian regime.
"EU will not hesitate on measures against interests of persons associated with repression and violence in Ukraine," he said.